This invention relates to improvements in internal combustion engine ventilation, in particular to means for ventilating the space between the exterior walls of an internal combustion engine and an associated encapsulation surrounding the same in spaced relation therewith, comprising a rotor of a radial fan arranged within the encapsulation on a shaft of the internal combustion engine and an air intake duct leading from an air inlet opening in the encapsulation to the suction side of the fan.
In a previously proposed ventilation system of the kind specified for application to an internal combustion engine which has been encapsulated for noise suppression, the encapsulation is secured by means of resonance-insulating elastic support elements on the engine block. Because of the elastic supports for the encapsulation on the engine and in view of unavoidable fitting tolerances, it is necessary to leave a comparatively wide gap between the air intake duct and the rotor wheel of the fan. Such gap gives rise to a certain degree of short-circuit flow from the pressure area following the fan towards the intake or suction side of the fan which reduces the effectiveness of the fan.
The present invention aims to avoid the disadvantages appertaining to this conventional arrangement and to provide a ventilation system which allows a highly aerodynamically efficient design of fan to be used without impairing the acoustic efficiency of the noise-suppressing encapsulation.